The present invention claims foreign priority under 35 USC 119 based on Japanese Patent Application No. 2002-358386, filed Dec. 10, 2002, the contents of which are incorporated herein by reference.
The present invention relates to an ink cartridge having a plurality of ink chambers, each ink chamber having a movable member that descends with ink consumption. The invention also relates to an ink jet printer incorporating such an ink cartridge as an ink supply source.
In the related art ink cartridge for an ink jet printer, a bag-type related art ink tank is constructed such that a flexible ink bag filled with ink is in a rigid plastic case. Alternatively, a foam-type ink tank is constructed such that ink-absorbent foam or felt is in a rigid plastic case.
However, related art ink tanks have various problems and disadvantages. For example, but not by way of limitation, the efficiency of drawing ink from the bag and the foam or felt is poor. Also, the filling efficiency of the ink is low. As a result, it is difficult to reduce the size of the ink tank. Further, the bag-type ink tank has a probability of ink leakage due to poor sealing of the ink bag.
Additionally, the ink bag can break, such that ink leaks out of the bag when the ink bag and the plastic case containing the ink bag rub during transport. Related art attempts to prevent the rubbing and the bag breakage have included increasing the rigidity and strength of the flexible material forming the ink bag. However, in this modified related art ink bag, a negative pressure for supplying ink increases, and various problems arise. For example, but not by way of limitation, the amount of consumed ink increases, and the amount of residual ink varies.
Also, in the related art foam-type ink tank, foreign materials may enter the ink supplied from the foam. The foreign materials enter the ink and flow into the print head, thereby causing clogging of the printer head.
FIG. 7 shows a related art ink cartridge 100. Four ink chambers 102(1) to 102(4) are disposed side by side, with their upper ends open within a case 101. An L-shaped waste ink chamber 110 extends from the upper parts of those ink chambers to the side parts thereof.
The ink chambers 102(1) to 102(4) respectively include lids 103(1) to 103(4), which are vertically movable along the inner peripheral surfaces 102a of those chambers. Ink outlets 104(1) to 104(4) are formed in the bottom surfaces of the four ink chambers 102(1) to 102(4). Ink reservoirs 105 are respectively formed by bottom surfaces 102b and the inner peripheral surfaces 102a of the ink chambers, and the movable lids 103(1) to 103(4).
The movable lids 103(1) to 103(4) are urged by spring members 106 in an upward direction. As a result, the ink reservoirs 105 experience negative pressure. The strength of an ink meniscus formed in a gap between each inner peripheral surface 102a and an associated one of those movable lids 103(1) to 103(4) is selected such that the ink meniscus is not broken by an ink suction force of the print head, which exerts pressure on the ink outlet.
The foregoing related art ink cartridge 100 may be used for a multi-color ink cartridge, in which different colors of ink are stored in the four ink chambers 102(1) to 102(4).
However, each of the movable lids 103(1) to 103(4) is held within an associated one of the ink chambers 102(1) to 102(4) by the ink meniscus formed in a gap between the inner peripheral surface 102a of the ink chamber and the outer peripheral surface of the movable lid to form the ink reservoir 105 in the lower side of the movable lid. Thus, the ink meniscus may break when impact is applied to the ink cartridge 100, so that ink leaks to the upper side of the movable lid (i.e., the side closer to the waste ink chamber 110).
When the ink leaks to the upper side of the movable lid, the leaked ink from the respective ink reservoirs 105 may mix with ink from other reservoirs. Then, the mixed ink may return to the respective ink reservoirs 105. In addition, since the waste ink chamber 110 is filled with an ink absorbing member of foam or felt, fine particles contained in the ink absorbing member may mix with the leaked ink and enter the ink reservoirs 105.